In the prior art, vibration actuators are known, which have an oscillator where an electromechanical conversion element and an elastic body are joined. The vibration actuators generate a progressive oscillatory wave (below referred to as progressive wave) at the elastic body by utilizing the expansion and contraction of the electromechanical conversion element. This progressive wave causes a relative movement member which is in pressure contact with the oscillator (elastic body) to be frictionally driven. In this type of vibration actuator, a highly elastic material, for example a metal material of stainless steel family or the like, is used for the elastic body in order to efficiently transmit the applied vibrations to the relative movement member.
In such a vibration actuator, frictional contact faces of the oscillator and the relative movement member exert a large effect on the stability, efficiency, and the like of the driving of the vibration actuator. Therefore, various attempts have been made to improve the durability and the like of the frictional contact faces.
For example, Patent Document 1 discloses a technique of providing a thermosetting resin film on driven faces (namely, frictionally contacting faces) of a driving body of a rotor and a stator.
Patent Document 1: Japanese Unexamined Patent Application No. 2009-232622